This invention relates to the application of cold or heat to affect heat transfer to or from the human or mammalian body. The necessity for such an application may arise in a wide range of circumstances. Most common are injuries, bruises, sprains, or other trauma to bone, muscle, ligaments, tendons, skin and other forms of mammalian tissue. The application of cold or cooling to reduce swelling, reduce pain and promote healing at the traumatized area of the human or mammalian body is often recommended. Similarly, the application of heat or heating to the human or mammalian body is used to warm up or "loosen-up" joint tissue such as ligaments or tendons prior to use to facilitate an increased range of motion prior to normal or strenuous physical activities.
Other circumstances in which the need for application of cold or heat therapy to the human or mammalian body may arise include post-surgical therapy to reduce pain and swelling and promote healing, as well as in orthopedic therapy, sports medicine therapy and rehabilitation programs and applications. Of particular importance are the areas of athletic injury and subsequent therapy, healing and rehabilitation in humans, and injury and subsequent therapy, healing and rehabilitation in thoroughbred race horses.
The most common method of achieving the desired cooling effect has been application of an ice bag to the desired therapy site. This method has several limitations. Ice bags can be cumbersome to apply, and in the case of animals, for example thoroughbred race horses, may be difficult to maintain on the therapy site. Ice bags can apply uneven cooling to the therapy site, are often difficult to contour to the area of the mammalian body to be treated, and the intensity of cooling is difficult to control. Often the application is either too cold, or not cold enough. A common ice bag has further limitations as well. As the ice melts, an ice bag may leak, causing inconvenience or more serious consequences. Finally, the static application of cold or cooling can become uncomfortable and unpleasant, usually resulting in the subject prematurely terminating the application before the full beneficial affect can be achieved.
A number of variations have been proposed to improve upon the ice bag or pack, but none fully addressed all of its shortcomings. For example, some have been known to use a bag of frozen peas (or other vegetables) as a substitute for an ice bag. The frozen peas allow more uniform cooling of the site, generally contour to the site better than a bag of ice cubes, and apply less severe cooling. Of course, this alternative has a number of drawbacks as well. A bag of frozen peas has limited available cooling capacity, and as with any bag, contouring to a part of the mammalian body such as the human knee can be difficult or impossible, resulting in uneven cold application.
Other variations on the basic ice bag or ice pack include a wrap or strap-on device which holds the source of cooling on the therapy site. These devices generally are designed for use on specific locations on the human body, and generally contour better to the therapy site and are held in place by means of belts or straps. These devices also have several shortcomings, however. Certain types have built-in reservoirs to provide a source of cooling, such as containers of frozen water. These devices must be kept frozen until ready to use, and once their cooling capacity is expired, they must be re-frozen before they can be used again. The intensity of cooling with these wrap or strap-on devices is also difficult to control, and they are capable of applying only static cooling to the site. There are also generally cumbersome, as the source of thermal cooling must be located entirely within the device and held at or on the therapy site.
Also available are chemical cold-packs comprised of two or more chemical substances stored separately in a flexible packet. When needed, the packet is manipulated, causing an internal seal to break and the chemical substances to mix. The substances, when mixed, have an endothermic reaction which causes the packet to cool. While these devices are useful in remote sites and in certain emergency situations, they afford little advantage over the ordinary ice bag. Furthermore, they can generally be used only one time, are of limited cooling capacity or duration, operate at one non adjustable temperature, and are prohibitively expensive for use in a regular cold therapy program.
More recently, a commercially available apparatus for accomplishing the desired cooling of the human knee has been developed which incorporates a cold reservoir consisting of a large cooler. The water within the cooler is circulated by means of a pump which circulates the cooled water from the cooler through a tube to a bladder and back trough a tube to the cooler. The bladder is applied to the therapy site and held in place by means of a wrap or strap device. This apparatus has many advantages over an ice pack or ice wrap. The cooler and source of cooling, generally ice, is held in a container separate from the therapy site. In this type of device, the rate of cooling is adjusted by increasing or decreasing the flow resistance by using a manually operated flow restriction valve or electrically setting the pump speed to a predetermined fixed value.
This apparatus also has several shortcomings. The device is incapable of supplying a measured and controlled cooling temperature to the therapy site, and is incapable of providing tactile stimulation to the therapy site. The device is also cumbersome in that the pump used to circulate the cooling fluid must be manually submerged in the cooler, and there is an ever-present danger of electrical shock due to the proximity of the electrical power cord and the circulating water.
The most common method for achieving the desired heating effect has been through the application of a hot water bottle or steamed towels to an injury site. As with similar cold therapy modalities, this form of heat therapy suffers from the same shortcomings in terms of ease of application and temperature regulation due to a lack of any temperature control mechanism at the injury site.